Primary immunodeficiency is a very rare, but devastating, condition in which there is a partial or total collapse or absence of one or more classes of immune responses. It is typified by recurrent or chronic life-threatening infections and by the necessity for its victims to live in rigorously controlled, sterile conditions. There is no existing treatment other than isolation of the patient from all potential sources of infection.
In secondary immunodeficiency, the immune system function is reduced and may appear as a result of age, disease or the use of certain therapies, such as cytostatic radiotherapy or chemotherapy for cancer. Patients whose immune system function is reduced are vulnerable to both viral and other infections, and treatment of such infections may be complicated and/or protracted.
Acquired immune deficiency syndrome (AIDS) is a recently identified syndrome in which a person's immune system after functioning normally ceases to function adequately. While AIDS resembles somewhat the clinical pathology of secondary immunodeficiency, it alone is uniquely characterized by a reduced ratio of helper to suppressor T-cell subsets.
The etiology of acquired immune deficiency syndrome is unknown and no effective treatment has yet been found. Because of the breakdown in the immune system, such individuals are highly vulnerable to infections and there has been a high mortality from opportunistic infections and Kaposi's sarcoma. See, e.g. "Immunocompromised Homosexuals" (Editorial) Lancet 1981; ii: 1325-6; Center for Disease Control, "Epidemiological Aspects of the Current Outbreak of Kaposi's Sarcoma and Opportunistic Infections", N. Engl. J. Med. 1982, 306: 248-52; Gerstoft et al., "Severe Acquired Immunodeficiency in European Homosexual Men", Br. Med. J. 1982, 285: 17-19. The two year mortality rate has been reported to be as high as 80%.
It has been known for some time that the thymus gland is connected with the immune functions of the body and therefore great interest has been indicated in substances which have been isolated from the thymus. Certain lymphocytes are differentiated within the thymus and leave as thymus derived cells, called T-cells, which circulate in the blood, to the lymph, spleen and lymph nodes. See, e.g., U.S. Pat. Nos. 4,002,602, 4,010,148, 4,082,737, 4,148,886 and 4,167,557. Attempts to restore cell mediated immunity by reviving the thymus dependent T-cell functions have been carried out in experimental animals and in humans by using several thymic extracts of different chemical, physical and biological activities. Bach, "Thymic Hormones: Biochemistry and Biological and Clinical Activity", Ann. Rev. Pharmacol. Toxicol., 17, 281 (1977); Trainin, "The Role of Thymic Hormones in Regulation of the Lymphoid System", in Loor et al (Eds.), B and T Cells in Immune Recognition (Wiley & Sons, London) 83-102 (1977). It has been observed that highly purified thymic factors are probably incapable of inducing in immunodeficient animals a T-cell dependent immune response body in vitro and in vivo. Masuda, V. "Abstract from the Symposium on "Immunodeficiency, its Nature and Etiological Significance in Human Disease", Tokyo, Sept. 13-15, 1976. This observation seems to support the assumption that several protein hormones contained in a thymic extract are required in order to achieve a proper range of activity.
It has now been discovered that a particular thymic extract, hereinafter referred to as TP-1, can successfully be used in stimulating the cellular immune system of a person having acquired immune deficiency syndrome. This discovery is particularly surprising because the etiology and prophylaxis of acquired immune deficiency syndrome is not known.
It is, therefore, the object of this invention to provide a method of stimulating the cellular immune system in a person having acquired immune deficiency syndrome. This and other objects of the invention will become apparent to those skilled in this art from the following detailed description.